Flood-lighting luminaire



J81!- 31, H DAHLKE FLOOD-LIGHTING LUMINAIRE Filed May 28, 1964 INVENTORYHeinz Dohl ke Fig.2

ATTORNEY United States Patent 3,302,015 FLOOD-LIGHTING LUMINAIRE HeinzDuhlke, Traunstein, Germany, assignor to Siemens-SchnckertwerkeAktiengesellscliaft, Erlangen, Germany, a corporation of Germany FiledMay 28, 1964, Ser. No. 370,907 Claims priority, application Germany,June 8, 1963, 5 45,220 6 Claims. (Cl. 240--4l.3)

In the case of luminaires employed for high output lamps of smalldimensions, e.g. floodlights, it is frequently necessary to screen outthe light source at the larger angles with respect to the vertical, e.g.from 80, because of the high intensity of illumination. It is knownpractice, in the case of floodlights fitted with a quartziodineincandescent lamp located within a channelshaped parabolic mirror, toincorporate thin screening plates in order to cut down the amount ofglare. These thin broad plates, which are set parallel to the symmetryplane of the channel-shaped mirror, are located only in the upper halfof the light-exit cross-section of the mirror. The light rays from theluminaire emerge in a well defined direction so that the major portionof the light is radiated out in the direction of the parabolas axis. Inmany cases, the fact that the region below the luminaire receives verylittle illumination constitutes a major drawback. In the illumination bymeans of floodlights of a building facade, a sporting arena, or anaircraft landing field, certain lighting conditions apply for which thelight-exit apertures of the floodlights are placed at differentpositions. In the case where horizontal surfaces are to be illuminated,the light-exit aperture is tilted in a downward direction in such a waythat the light reflected from the mirror is directed in a broad fan andwith little vertical scatter onto the approximate center of the area tobe illuminated. In such a case, the naked high-power lamp radiatesglare-producing light directly out over a large angle and hence upwardsinto the air. Such light beams could seriously interfere with airtraflic.

The present invention enables an improvement to be effected in aluminaire suitable for use in a high output quartz-iodine lamp of smalldimensions which is located in a channel-shaped mirror and used as afloodlight, the said high-output lamp being provided with a means fordeflecting the light. According to the present invention, thechannel-shaped mirror also acts as a screen or cover for the auxiliarymirror serving the lamp and is fitted with a cover-glass equipped withprisms which serve to direct the light into the region located below theprincipal light-emitting direction of the channelshaped mirror.

The luminaire made in accordance with the present invention may, forexample, be fitted with a quartziodine incandescent lamp or with a highpressure mercury vapor lamp. It is also possible to use a high pressure,high-output sodium vapor lamp in whose outer envelope is located adischarge tube which is about the same size as a pencil. Despite thehigh luminosity of these lamps, exceptionally good anti-glarecharacteristics are attained as a result of the screening in lamps, inaccordance with the present invention. In the illumination of anairfield landing strip by means of a floodlight made in accordance withthe present invention, the upward-directed light from the high-outputlamp which could hinder air trafiic is screened by the auxiliary mirror,but it is not lost. The light falling on such auxiliary mirror isdirected onto the channel-shaped mirror and reflected into the principalradiating direction. By this means, part of the light is so deflected bythe mediately below the floodlights.

The invention is illustrated schematically in the accompanying drawings,in which:

FIGURE 1 is a vertical cross section of the luminaire of the presentinvention taken on the line 1-1 in FIG. 2;

FIG. 2 is a longitudinal section, on a reduced scale, taken through theaxis of the luminaire shown in FIG. 1 on the line IIII;

FIG. 3 is a cross section of a luminaire cover-glass fitted withinward-facing prisms; and

FIG. 4 is a cross section of a luminaire cover-glass having inward andoutward facing prisms.

The luminaire, shown for a high-output lamp of small dimensions,consists of a floodlight equipped with a quartz-iodine incandescent lamp1, the latter being replaceable by a high-pressure mercury vapor lampfitted with a clear glass outer envelope, or a high pressurehigh-intensity sodium vapor lamp fitted with an ellipsoidal outerenvelope. The channel-shaped mirror 2 which encloses lamp 1 has, forexample, a parabolic cross section with lamp 1 located on its focalline. The light rays are collected into a well-defined parallel bundleby means of channel-shaped mirror 2. Additional light deflectors areprovided in order to obviate glare.

According to the invention, channel-shaped mirror 2 is fitted with anauxiliary mirror 3 and is closed by a cover-glass 4 which is providedwith prisms. The additional light-deflecting means are accordinglyconstituted of auxiliary mirror 3 and prisms 5. In this regard,auxiliary mirror 3 simultaneously acts as a screen for lamp 1, whileprisms 5 produce a deflection of part of the light, which would havebeendirected into the distance, into the region located below the mainradiating direction H of channel-shaped mirror 2. This lower region isilluminated by rays I, II, III and IV. Appropriately, prisms 5 aresituated in the lower-edge-region 6 of channel-shaped mirror 2,preferably in the approximate lower half of cover-glass 4.. For thispurpose, prisms 5 are differently proportioned, i.e. their thicknessincreases as longitudinal edge 6 is approached and, as a result, raysIV, which are nearest longitudinal edge 6, undergo the greatestdeflection, a deflection which is appreciably greater than that of raysI. The angle of diffraction of prisms 5 can vary in a continuous manner.

Prisms 5 can be advantageously formed on one or on both sides ofcover-glass 4. In FIG. 1, prisms 5 are formed on the outside ofcover-glass 4, in FIG. 3 they are formed on the inside, while in FIG. 4they are shown formed on both sides of the cover-glass. It is alsopossible to apply only part of prisms 5 on the outside of a given cover4, while other portions may be applied to the inside and also on bothsides. Prisms 5 can also be located as far as symmetry plane S ofchannel-shaped mirror 2, but they can also terminate above or below thisplane.

For convenience, auxiliary mirror 3 has the form of a channel whosecross section forms part of a circle. In this regard, the center of thecircle, M, can be arranged to lie away from the axis of the lamp, andpreferably on the periphery of the lamps enclosing envelope. The upperlimiting edge 7 of auxiliary mirror 3 lies in a plane which is definedby the axis of the lamp and the upper longitudinal edge 8 of channelshaped mirror 2. The lower limiting edge 9 of auxiliary mirror 3 liespreferably in a plane which passes through the lamps axis and standsperpendicular to the light-exit planes of channel-shaped mirror 2. Thelower limiting edge 9 of auxiliary mirror 3 can be arranged to lie inthe symmetry plane S of channel-shaped mirror 2. The border-edges 10, 11(FIG. 2) of auxiliary mirror 3 also lie in a plane which is defined byan end of lamp 1 and one of the short limiting edges 12, 13 of thelightexit opening of channel-shaped mirror 2.

I claim as my invention:

1. A floodlighting luminaire comprising: an elongated channel-shapedprimary mirror having a front opening and a focus describing a line; ahigh-intensity elongated integral lamp mounted along and proximate thefocal line of said primary mirror; said luminaire having a mainradiation direction for radiations generated by said lamp and reflectedby said primary mirror; a lighttransmitting cover member fitting overthe front opening of said primary mirror, and said cover member dividedinto upper and lower sections; an elongated auxiliary mirror spaced fromsaid lamp and positioned between said lamp and the upper section of saidcover member to intercept direct radiations emanated by said lamp towardsaid cover member and above the main radiation direction of saidluminaire; and prisms provided on the lower section of said cover memberto retract light striking same into the region located below the mainradiation direction of said luminaire.

2. The luminaire as specified in claim 1, wherein said prisms aresubstantially confined to the lower section of said cover member, andsaid prisms have such varying configurations that each prism refractslight downwardly more than that prism directly thereabove.

3. A floodlighting luminaire comprising: an elongated channel-shapedparabolic mirror having a front opening and a focus describing a line; ahigh-intensity lamp elongated integral mounted along and proximate thefocal line of said parabolic mirror; said luminaire having a mainradiation direction for radiations generated by said lamp and reflectedby said parabolic mirror; a lighttransmitting cover member fitting overthe front opening of said parabolic mirror, and said cover memberdivided into upper and lower sections; an auxiliary elongated mirrorhaving a cross section which forms part of a circle whose centerdescribes a line positioned slightly above the focal line of saidparabolic mirror, and said auxiliary mirror spaced from said lamp andpositioned between said lamp and the upper section of said cover memberto intercept direct radiations emanated by said lamp toward said covermember and above the main radiation direction of said luminaire; andprisms provided on the lower section of said cover member to refractlight striking same into the region located below the main radiationdirection of said luminaire.

4. The luminaire as specified in claim 3, wherein the lower edge of saidauxiliary mirror lies proximate a plane parallel to the main radiationdirection of said luminaire and which passes through the focal line ofsaid parabolic mirror, and the lower edge of said auxiliary mirror isapproximately perpendicular to the main radiation direction of saidluminaire.

5. The luminaire as specified in claim 3, wherein the upper edge of saidauxiliary reflector lies proximate the plane described by the focal lineof said parabolic reflector and the upper edge of said parabolicreflector.

6. The luminaire as specified in claim 3, wherein the upper section andthe lower section of said cover member are of approximately equal sizeand said prisms are substantially confined to the lower section of saidcover member.

References Cited by the Examiner UNITED STATES PATENTS 2,142,964 1/1939Godley 240-414 2,277,563 3/1942 Scott et al. 240-4l.4 X 2,380,849 7/1945Kolb 2404l.3 X 3,222,516 12/1965 Miles 2404l.3 X

JOHN M. HORAN, Primary Examiner.

NORTON ANSHER, Examiner.

C. R. RHODES, Assistant Examiner.

1. A FLOODLIGHTING LUMINAIRE COMPRISING: AN ELONGATED CHANNEL-SHAPEDPRIMARY MIRROR HAVING A FRONT OPENING AND A FOCUS DESCRIBING A LINE; AHIGH-INTENSITY ELONGATED INTEGRAL LAMP MOUNTED ALONG AND PROXIMATE THEFOCAL LINE OF SAID PRIMARY MIRROR; SAID LUMINAIRE HAVING A MAINRADIATION DIRECTION FOR RADIATIONS GENERATED BY SAID LAMP AND REFLECTEDBY SAID PRIMARY MIRROR; A LIGHTTRANSMITTING COVER MEMBER FITTING OVERTHE FRONT OPENING OF SAID PRIMARY MIRROR, AND SAID COVER MEMBER DIVIDENDINTO UPPER AND LOWER SECTIONS; AN ELONGATED AUXILIARY MIRROR SPACED FROMSAID LAMP AND POSITIONED BETWEEN SAID LAMP AND THE UPPER SECTION OF SAIDCOVER MEMBER TO INTERCEPT DIRECT RADIATIONS EMANATED BY SAID LAMP TOWARDSAID COVER MEMBER AND ABOVE THE MAIN RADIATION DIRECTION OF SAIDLUMINAIRE; AND PRISMS PROVIDED ON THE LOWER SECTION OF SAID COVER MEMBERTO REFRACT LIGHT STRIKING SAME INTO THE REGION LOCATED BELOW THE MAINRADIATION DIRECTION OF SAID LUMINAIRE.